The present invention relates to a portable flare stack.
It has been a common practise in the oil and gas industry to vent gas to atmosphere when servicing a gas well. For example, when fracturing a well to improve flow rates, it has been common to vent gas to atmosphere for between twelve and twenty four hours in order to rid the well of residual fracturing fluids which might otherwise plug the well.
In recent years there have been environmental protection laws passed that prohibit venting of gas to atmosphere. Any excess gas produced by a gas well must be either captured or sent to a gas flare. There is, therefore, a need for a portable flare stack that can readily be transported to gas wells to flare gas for time durations of twenty four hours or less.
U.S. Pat. No. 4,255,120 entitled xe2x80x9cPortable Safety Flare for Combustion of Waste Gasesxe2x80x9d which issued to Straitz in 1981 discloses a portable gas flare built onto a truck and trailer unit. This vehicle mounted portable safety flare is too large and, consequently, too expensive to use on short duration gas flaring jobs involving relatively small volumes of gas.
What is required is a smaller portable flare stack that is suited for use for short duration gas flaring involving relatively small volumes of gas.
According to the present invention there is provided a portable flare stack which includes a base having a first end and a second end. A tubular conduit extends substantially the length of the base. The tubular conduit has a flaring end and a gas connection end. The tubular conduit is pivotally mounted at one of the first end and the second end of the base for movement between a travel position and a flaring position in which the tubular conduit extends substantially perpendicular to the base. A counterweight is positioned adjacent to the gas connection end of the tubular conduit. A drive mechanism is provided for moving the tubular conduit, as required, between the travel position and the flaring position.
The portable flare stack, as described above, is simple and light weight. It is preferred that the base is a trailer chassis having ground engaging wheels at the second end and a hitch at the first end. The trailer chassis can be moved on the ground engaging wheels with the tubular conduit in the travel position. Once at a well site, the tubular conduit can rapidly be pivoted into the gas flaring position and the gas connection end of the tubular conduit connected to a source of gas. The movement of the tubular conduit between the travel position and the gas flaring position is made easier by the counterweight which reduces the force necessary to effect the required pivotal movement. This enables a simpler form of drive mechanism to be used for moving the tubular conduit between the travel position and the flaring position. The preferred drive mechanism includes a cable supported on a reel which is rotatably mounted to the chassis. The cable has a free end secured to the gas connection end of the tubular conduit. The cable extends over several direction altering pulleys. Rotation of the reel in a first direction shortens the cable. Rotation of the reel in a second direction lengthens the cable. The cable exerts a force upon the gas connection end of the tubular conduit to pivotally move the tubular conduit between the travel position and the flaring position.
Although beneficial results may be obtained through the use of the portable flare stack, as described above, it is preferred that the chassis have an extendible and retractable support leg at the first end, so that the first end of the trailer chassis is supported when the hitch is disconnected from the tow vehicle. It is also preferred that the chassis have outrigger support legs at the second end.
Although beneficial result may be obtained through the use of the portable flare stack, as described above, it is preferred that a support be positioned adjacent the first end to receive the tubular conduit when the tubular conduit is in the travel position. This prevents jarring impacts during travel from damaging the pivotal connection by which the tubular conduit is mounted""to the trailer chassis.